Device for machining a substrate and a method for this purpose

ABSTRACT

In a device for machining, in particular etching and/or developing, substrates, in particular wafers, in particular etching and/or developing, having a turntable, the turntable has a Venturi gap.

BACKGROUND OF THE INVENTION

The invention relates to a device and method for machining, inparticular etching and/or developing, substrates, in particular wafers.

The prior art discloses many and various devices for machiningsubstrates. In the field of semiconductors, in particular, rotary orspin coaters for applying photoresist to substrates are known. Theserotary or spin coaters are also referred to as “coaters”. Wafers orglass disks or the like are used as substrates. In addition to these“coaters”, the prior art also discloses devices for machining, inparticular etching and/or developing, substrates.

In this context, attention is drawn, in particular, to EP 1 743 220 A1.The device described in the prior art for the rotary coating ofsubstrates describes a spin coater, which has a rotatable substratetable for horizontal placement of a substrate. The machining medium isdistributed by rotating the substrate table. One particular problem isthat the machining medium also penetrates to the rear side of thesubstrate to be processed and modifies it. This leads to damage to therear side, particularly in the case of double-sided wafers.

It is the object of the invention to provide a device for machining, inparticular etching and/or developing, substrates, in particular roundwafers, in order to machine a wafer in such a way that the rear sidethereof is not damaged and/or contaminated, and to provide a method forthis purpose.

SUMMARY OF THE INVENTION

The foregoing object is achieved by providing a device for machining, inparticular etching and/or developing, substrates, in particular roundwafers, has a turntable, which has a Venturi gap. Compressed air or someother medium is preferably delivered through the Venturi gap. Thisresults in several advantages. The first advantage is that, as a result,the substrate is drawn in in accordance with the Venturi principle, andis held on the turntable and not thrown off, despite the rotation of theturntable. Another advantage is that the rear side remains clean and thetreatment medium cannot run onto the rear side and contaminate or damageit. This is particularly advantageous for substrates that are coated ormachined on both sides.

It is expedient if the Venturi gap has a gap size of 0.01 mm to 0.1 mm,preferably 0.58 mm. Fundamentally, the gap size is dependent on thesubstrate thickness and size to be machined.

In typical embodiments, the device comprises a compressed air source.This has the advantage that the Venturi gap can be supplied withcompressed air or pressure medium. As a particularly preferred option,the compressed medium source is suitable for producing an excesspressure of 4 to 8 bar, preferably 6 bar.

The device preferably comprises defined edges in order to achieve adefined pressure distribution, especially in the Venturi gap. As aparticularly preferred option, the edges are arranged upstream of theVenturi gap.

In typical embodiments, the device comprises at least one hole. The atleast one hole is preferably arranged in a central area of theturntable, said area facing a substrate. A plurality of holes ispreferably arranged in the upper surface. This has the advantage that areduced pressure or vacuum is prevented from arising between theturntable and a central area of the substrate. This is advantageoussince it prevents the substrate from bending or being deformed in someother way in the central area.

In typical embodiments, the turntable has a dish shape. This has theadvantage that the turntable is very robust and is easy and economicalto produce.

In typical embodiments, the device has a diffuser. The diffuser ispreferably inserted into an interior space of the turntable.

As a particularly preferred option, the diffuser forms the Venturi gapwith the turntable. As an even more preferred option, the upper surfaceof the diffuser at least partially forms an area in which a vacuum canform between the wafer and the upper surface.

As a particularly preferred option, the underside of the diffuser formsan edge which ensures defined pressure distribution of the pressuremedium between the upper surface of the turntable and the underside ofthe diffuser.

As a particularly preferred option, the device, in particular theturntable, comprises a plurality of pins, preferably three or four pins.The pins advantageously have the effect that the wafer slides into apredefined position between the pins. When the wafer is resting on oneof the pins, this is detected by a sensor unit, and the machiningoperation is not set in motion.

In typical embodiments, the device comprises a turntable that has aplurality of grooves. The grooves are preferably arranged on acircumferential edge of the turntable. The grooves are preferablyarranged in such a way that the wafer or the substrate, when correctlypositioned, projects over the grooves.

In typical embodiments, the device comprises a gripper. The gripperpreferably comprises a plurality of lifting pins. The lifting pins ofthe gripper are preferably arranged at the same angular intervals as thegrooves on the turntable. The lifting pins of the gripper are preferablyarranged on a diameter which corresponds to a diameter on which thegrooves of the turntable are arranged. This has the advantage that thelifting pins of the gripper can engage in the grooves of the turntable,ensuring that the wafer or the substrate comes to rest on the liftingpins of the gripper.

It is furthermore advantageous that the gripper can also be used todeposit the wafer on the table without damaging the gripper.

In typical embodiments, the turntable is designed in such a way that aflow of medium or air emerging from the Venturi gap is directed in anarea underneath an upper surface of the turntable. This has theadvantage that better coating is achieved. This is possible because aflow over an upper surface and hence over a substrate is avoided orreduced. Reducing or avoiding a flow over the substrate ensures betterapplication of coating. First of all, there is less turbulence in thecoating medium during application. Moreover, the applied coating is notsubjected to any flow either, and, as a result, a better drying resultis achieved. Finally, the avoidance or reduction in flow over the uppersurface of the substrate table and/or of the substrate avoids thedisturbance of dirt or particles which could fall on the fresh coating.

For this purpose, the turntable preferably has a chamfer. As aparticularly preferred option, the chamfer is arranged on an uppercircumferential edge of the turntable, in particular a bottom part ofthe turntable.

The chamfer preferably has a width of 0.5 mm to 10 mm, in particular awidth of 1 mm to 5 mm, preferably 3 mm. The chamfer preferably has aheight of 0.5 mm to 10 mm, in particular a width of 1 mm to 5 mm,preferably 3 mm.

It is expedient if an angle formed between the axis of an upper surfaceof the turntable and the axis of an upper surface of the chamfer isbetween 5° and 85°, preferably 20 to 50°, in particular 48°.

Protection is sought separately for a method for machining, inparticular etching and/or developing, substrates, in particular roundwafers, comprising the following steps: rotation of the turntable,application of a machining medium to the turntable, removal of asubstrate.

In typical embodiments, a slide is positioned in order to place thesubstrate. During this process, the substrate rests on the slide. Theslide is preferably a linear motion element. It is expedient if theslide is moved in such a way that the substrate is positioned over theturntable. The gripper is then positioned under the slide and thesubstrate in such a way that the substrate rests on the three liftingpins of the gripper. It is expedient if the slide is removed from underthe substrate, preferably by means of a linear motion. In a subsequentstep, the substrate is preferably deposited on the turntable, inparticular between the pins of the turntable. Deposition is preferablyaccomplished by means of a relative movement between the turntable andthe gripper along an axis of rotation of the turntable, wherein thelifting pins of the gripper move through the grooves of the turntable.

In typical embodiments, the removal of a substrate is accomplished in asimilar manner. For this purpose, a gripper is preferably positionedunder the substrate on the turntable, thus enabling the lifting pins ofthe gripper to engage in the grooves of the turntable from below.

By virtue of a relative movement between the turntable and the gripperalong an axis of rotation of the turntable, the lifting pins of thegripper engage in the grooves of the turntable, with the result that thesubstrate rests on three points of the gripper, and the substrate istherefore raised from the turntable.

As a particularly preferred option, the slide is positioned under thesubstrate, and the gripper is removed from under the substrate. Thesubstrate is then moved with the slide away from the turntable.

The term “relative movement” is intended to indicate that it is possibleboth for the gripper to be moved along the axis of rotation in thedirection of the turntable and for the turntable to be moved along theaxis of rotation in the direction of the gripper by means of a liftingmovement.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and details of the invention will becomeapparent from the following description of preferred embodiments andfrom the drawings, in which

FIG. 1 shows a schematic illustration of a perspective view of aturntable of a device according to the invention;

FIG. 2 shows a schematic illustration of a sectioned side view of theturntable shown in FIG. 1;

FIG. 3 shows a schematic illustration of a perspective view of a gripperfor a device according to the invention;

FIG. 4 shows a schematic illustration of a perspective view of anotherembodiment of a turntable for a device according to the invention with awafer;

FIG. 5 shows a schematic illustration of a side view of anotherembodiment of a turntable of a device according to the invention; and

FIG. 6 shows a schematic illustration of a perspective view of theturntable shown in FIG. 5.

DETAILED DESCRIPTION

FIG. 1 shows a turntable 1 for a device according to the invention. Theturntable 1 has an upper surface 2 for a substrate, in particular awafer. The turntable 1 has a circular shape. The turntable 1 furthermorehas a Venturi gap 3. The Venturi gap 3 is arranged at the upper surface2 of the turntable 1.

As can be seen from FIG. 2, the turntable 1 comprises a dish-shapedbottom part 4.

A diffuser 5 is inserted into the dish-shaped bottom part 4 of theturntable 1. The upper surface 6 of the diffuser 5 forms part of theupper surface 2.

The circumferential edge 7 of the diffuser 5 and an inner rim 8 of thedish-shaped bottom part 4 of the turntable form the Venturi gap 3.

In the embodiment under consideration, the Venturi gap has a height of0.58 mm. The height is measured from a bottom part upper surface 9 ofthe dish-shaped bottom part 4 to an upper edge 10 of the diffuser 5.

The turntable 1 has an axis of rotation D.

The diffuser 5 is inserted into the dish-like bottom part 4 of theturntable 1 in such a way that a gap 11 is formed between the diffuser 5and the turntable 1. Defined edges 12 project into the gap 11. Thepurpose of the edges 12 is to ensure a defined pressure distribution ofa pressure medium, in particular compressed air, flowing through thechannel 11 into the Venturi gap 3. The edges 12 are formed on anunderside of the diffuser 5.

The turntable 1 furthermore comprises a plurality of holes 13. The holes13 are introduced into the diffuser 5.

The turntable 1 has a duct 14. A compressed air or compressed mediumsource 33 is connected to one end 15 of the duct 14.

The turntable 1 has a plurality of pins 16. These are used to positionthe substrate or wafer. By virtue of the fact that the substrate comesto rest only between the pins 16, there is the advantage that preciselydefined positioning between the pins can be accomplished. Moreover, thisadvantageously makes it possible, using a sensor device (not shown), todetect whether the substrate or wafer has come to rest in the predefinedposition.

The turntable according to the invention shown in FIGS. 1 and 2 operatesas follows:

A substrate (not shown), in particular a round wafer, is placed on theturntable 1 of FIGS. 1 and 2.

The turntable 1 is supplied with compressed air by means of a compressedair source connected to the end 15 of the duct 14. In the process,compressed air flows into the duct 14 through the gap 11 and out of theVenturi gap 3 between the bottom part upper surface 9 of the bottom part4 and the wafer or substrate. As a result, in accordance with theVenturi principle, a reduced pressure is produced, holding the wafer orthe substrate (not shown) on the turntable 1 despite a rapid rotarymotion of the turntable 1 about the axis of rotation D.

Moreover, this prevents treatment medium, e.g. etchant or developer,applied to an upper side of the substrate from running onto a rear sideof the medium and damaging or modifying the latter.

Compressed air flows out of the duct 14, between the upper surface 2 andthe substrate or wafer, through the holes 13. This prevents theformation, in the area of the holes 13, of a vacuum or a reducedpressure, which would bend the substrate downward, deform it and/ordamage it.

FIG. 3 shows another embodiment of a turntable 26. Resting on the latteris a substrate 17. The construction of turntable 26 is substantiallysimilar to that of turntable 1.

Turntable 26 furthermore has a plurality of grooves 18, 19 and 20. Thegrooves are introduced at a circumferential edge 25 of the turntable 26and the length thereof corresponds to a height of the turntable.

Moreover, a device according to the invention comprises a gripper 21, asillustrated in FIG. 4. The gripper 21 has three lifting pins 22, 23 and24. The lifting pins 22 to 24 are arranged on a diameter d. The diameterd corresponds substantially to a diameter of a turntable 1 or 26.

The grooves 18, 19 and 20 are arranged at the same angular intervals asthe lifting pins 22, 23 and 24. The grooves 18, 19 and 20 are preferablylikewise arranged on the diameter d.

The device according to the invention having a turntable 26 operates asfollows:

In order to deposit the wafer 17 on the turntable 26, it is positionedby means of a slide (not shown) at a distance above the turntable 26which corresponds at least to the height of the slide.

The gripper 21 is then moved under the wafer 17, with the result thatthe wafer 17 comes to rest by its edges on the three lifting pins 22, 23and 24.

By means of a relative movement between the turntable 26 and the gripper21, i.e. either by lowering the gripper 21 in the direction of theturntable 26 or raising the turntable 26 in the direction of the gripper21, the wafer 17 is then deposited on an upper surface of the turntable26, as shown in FIG. 3. During this process, the lifting pins 22, 23 and24 slide through the grooves 18, 19 and 20 of the turntable 26 of FIG.3.

The gripper 21 is moved relative to the turntable 26 in such a way thatthe lifting pins 22, 23 and 24 can be moved downward out of the grooves18, 19 and 20 in arrow direction P, and the gripper 21 is then removedfrom the turntable 26 again.

The wafer 17 can then be machined, using etchant or developer forexample.

In order to remove the wafer 17 from the turntable 26, the procedure issubstantially similar to that for deposition but in reverse.

The gripper 21 is positioned at the turntable 26, under the turntable26, and is then moved with the lifting pins 22, 23 and 24 into thecorresponding grooves 18, 19 and 20, counter to arrow direction P. As aresult, the wafer 17 rests on the upper side of the lifting pins 22, 23and 24 and is moved away from the turntable 26 with the gripper 21.

The slide (not shown) is then moved under the wafer 17, and the wafer 17is removed from the area of the turntable 26 together with the slide.

FIG. 5 shows another turntable 27. Turntable 27 is of substantiallysimilar design to either of turntables 1 and 26. Turntable 27 comprisesa chamfer 28. This can also be seen in the perspective illustration ofthe turntable 27 in FIG. 6.

With the chamfer 28, an upper edge on a circumference 29 of theturntable 27 has been removed.

The chamfer 28 is produced in a bottom part 30. Bottom part 30 is ofsubstantially similar design to bottom part 4.

The chamfer 28 has the effect that a medium, in particular air, is blownout of a Venturi gap 31 and diverted in arrow direction K. This isadvantageous because the medium, in particular the air, is directed intoa region below the turntable 27. This has the advantage that unwantedair turbulence above an upper surface 32 of the turntable 27 is avoidedand/or reduced. This is advantageous because better coating of asubstrate is achieved as a result. This is possible because the coatingis not subjected to any flow when there is a reduced flow over the uppersurface of the turntable and/or of the substrate and also because fewerparticles can be deposited on the coating by an air flow.

In the case of turntable 27, a flow emerging from the Venturi gap 31 isdiverted in the direction of a slope of the chamfer 28 or more steeplyby an upper surface 32 of the turntable 27 into an area under an uppersurface of the turntable 27.

In the embodiment under consideration, the chamfer 28 has a width b of0.5 mm to 10 mm, in particular a width of 1 mm to 5 mm, preferably 3 mm.The chamfer 28 preferably has a height h of 0.5 mm to 10 mm, inparticular a width of 1 mm to 5 mm, preferably 3 mm.

1. A device for machining a substrate comprising a turntable having anupper surface adapted to receive a substrate, a bottom part and aVenturi gap defined between the upper surface and the bottom parts. 2.The device according to claim 1, wherein the turntable is provided witha duct which receives a pressure medium from a pressure medium source.3. The device according to claim 2, wherein the turntable is providedwith at least one hole for allowing the pressure medium to escape fromthe duct.
 4. The device according to claim 1, wherein the turntable hasa dish shape.
 5. The device according to claim 1, wherein a diffuser isinserted into the bottom part of the turntable and forms the Venturigap.
 6. The device according to claim 1, wherein the turntable has anouter edge provided with a plurality of grooves.
 7. The device accordingto claim 6, wherein a gripper has a plurality of lifting pins whichmatch with the plurality of grooves.
 8. The device according to claim 1,wherein the turntable has a chamfer on the bottom part.
 9. A method formachining a substrate on a turntable comprising the steps of: placing asubstrate on a turntable having a Venturi gap; supplying the Venturi gapwith a pressure medium; rotating the substrate on the turntable;applying a machining medium to the substrate; and removing the substratefrom the turntable.
 10. The method according to claim 9, wherein thestep of placing the substrate comprises the following steps: positioningof the substrate on a slide; movement of the slide so that the substrateis positioned over the turntable; positioning a gripper under thesubstrate so that the substrate rests on three lifting pins of thegripper; removal of the slide from under the substrate; and depositionof the substrate on the turntable by means of a relative movementbetween the turntable and the gripper along an axis of rotation (D) ofthe turntable, wherein the lifting pins of the gripper engage in thegrooves of the turntable.
 11. The method according to claim 9, whereinthe step of removing a substrate comprises the following steps:positioning of a gripper under the substrate on the turntable; executionof a relative movement between the turntable and the gripper along anaxis of rotation (D) of the turntable, wherein lifting pins of thegripper engage in grooves on the turntable, with the result that thesubstrate rests on three points of the gripper; positioning a slideunder the substrate; removal of the gripper from under the substrate;and movement of the slide with the substrate.